Recent trends in sulphur dioxide air pollution in the Sheffield urban region

A study has been made of changes in the levels of SO₂ in the Sheffield region from 1968 to 1975. There was a marked decrease in the levels since 1970 during both winter and summer seasons. Although a series of mild winters could have contributed to the reduction in SO₂ the dominant influence appears to be the substantial increase in the use of sulphur-free fuels (natural gas and purified coke-oven gas) in industry; emissions from a local power station appear to bear no clear relationship to the SO₂ trend changes. The lower SO₂ levels have allowed the identification of comparatively high levels which may have resulted from the import of pollutants from more distant sources.